The verse "And no Prophet could (ever) be false to his trust" was revealed about a red velvet. When it was found missing on the day of Badr, some people said; Perhaps the Messenger of Allah ﷺ has taken it. So Allah, the Exalted, sent down "And no prophet could (ever) be false to his trust" to the end of the verse. Abu Dawud said: In the word yaghulla the letter ya has a short vowel a.  

ابْنُ عَبَّاسٍ ؓ نَزَلَتْ هَذِهِ الآيَةُ { وَمَا كَانَ لِنَبِيٍّ أَنْ يَغُلَّ } فِي قَطِيفَةٍ حَمْرَاءَ فُقِدَتْ يَوْمَ بَدْرٍ فَقَالَ بَعْضُ النَّاسِ لَعَلَّ رَسُولَ اللَّهِ ﷺ أَخَذَهَا فَأَنْزَلَ اللَّهُ ﷻ { وَمَا كَانَ لِنَبِيٍّ أَنْ يَغُلَّ } إِلَى آخِرِ الآيَةِ  

[Machine] This verse was revealed on the day of Badr, "And it is not for a prophet to take captives". It was revealed regarding a red camel that was lost on the day of Badr. Some people said, "Perhaps the Messenger of Allah ﷺ took it." So Allah revealed, "And it is not for a prophet to take captives."  

نَزَلَتْ هَذِهِ الْآيَةُ يَوْمَ بَدْرٍ {وَمَا كَانَ لِنَبِيٍّ أَنْ يَغُلَّ} فِي قَطِيفَةٍ حَمْرَاءَ فُقِدَتْ يَوْمَ بَدْرٍ فَقَالَ بَعْضُ النَّاسِ لَعَلَّ رَسُولَ اللهِ ﷺ أَخَذَهَا فَأَنْزَلَ اللهُ ﷻ {وَمَا كَانَ لِنَبِيٍّ أَنْ يَغُلَّ}  

[Machine] Narrated by Ibn Abbas: "It is not fitting for a prophet to have prisoners of war until he has thoroughly subdued the land. You (Muslims) have not done so, but Allah has done this in order to deliver the believers from the hands of the disbelievers. And He is most Forgiving, Most Merciful." (Qur'an 8:67)  

عَنِ ابْنِ عَبَّاسٍ {مَا كَانَ لِنَبِيٍّ أَنْ يَغُلَّ} قَالَ فِي قَطِيفَةٍ حَمْرَاءَ فَقَدُوها يَوْمَ بَدْرٍ فَقَالُوا أَخَذَهَا فَنَزَلَتْ {وَمَا كَانَ لِنَبِيٍّ أَنْ يَغُلَّ}